The present invention relates to the art of fluid ejection devices and, more particularly, to inkjet printers which use a plurality of pens supported in a page wide array in a frame referred to herein as a printbar which extends across a path of movement of media on which printing is to take place. The individual pens used in this field usually comprise generally rectangular configured fluid containing housings of molded plastic or other suitable material so that a number of pens can be aligned end-to-end in the printbar. Maximization of the size of the pens for ease of manufacture and close positioning of the pens in the printbar without pen-to-pen contact is important for accurate ink drop placement and in keeping size of the printer footprint to a minimum. For these reasons it is considered particularly advantageous to utilize pens which have protruding fore and aft lower orifice array portions on opposite sides of the lower portion of the pen so that the pens can be aligned with the fore and aft portions of adjacent pens in a side-to-side or nested relationship. These pens are rotationally symmetrical about a vertical axis. Electrical interconnects comprising conductive contacts arranged in a pattern are provided on opposite sides of the pen and mating electrical contacts are mounted on the frame for engagement with the interconnects on the pens for transmitting power to control the ejection of fluid from the pens. The pens must be closely and accurately positioned without contacting each other and they must each be stabilized against linear and rotational movement in the spaces on the printbar in which they are mounted.
Microscopic fluid droplets are ejected usually downwardly from thermal or piezoelectric printheads onto media on which a print pattern is to be produced from orifice plates mounted on the lower surfaces of the pens. The need for precise alignment of the pens relative to the frame or printbar on which they are supported is apparent to those skilled in the art.
The present invention therefore provides a method of positioning one or more fluid ejection devices such as an inkjet pen which ejects fluid in a first (Z) direction in a support, said device having electrical interconnects on opposite sides of said device which resiliently engage spaced electrical interconnects on said support which are spaced in a second (X) direction substantially orthogonal to said first direction, comprising inserting said device in said first direction into a mounting location in said support until said device engages said support and engaging datum surfaces on said opposite sides of said device located proximate opposite ends of said device with datum surfaces on said support during insertion of said device to resist rotation of said device about an axis parallel to said first direction.
The present invention further provides a fluid ejection assembly comprising a frame and one or more fluid ejection devices positioned in aligned mounting locations on said frame, the or each device comprising a housing for containing fluid, electrical interconnects on opposite sides of said housing and first datum surfaces on said opposite sides of said housing located between an interconnect and one of spaced ends of said housing, said frame including supports engageable with said device to position said device in a first (Z) direction in said mounting location and positioning surfaces on said frame engageable with said first datum surfaces on said opposite sides of said housing.